1. Field of the Invention
This invention relates to a method of manufacturing a semiconductor device, and specifically to a technique for preventing stacking faults, especially, oxidation induced stacking faults (OSFs), from being generated on a silicon surface at a silicon oxidation step.
2. Description of the Related Art
Various kinds of crystal defects in LSIs have been widely studied and reported by many documents. Among these researches concerning crystal defects, a method for preventing crystal defects, especially OSFs from being produced after a heat treatment in an LSI manufacturing process is actively studied.
For instance, it is reported that OSFs are caused by (1) defects mechanically formed on a wafer surface, (2) metallic contaminations, (3) oxidized depositions, and the like. This kind of reports, however, only describe the occurrence causes of OSFs, and fail to teach how to control it. In addition, in many cases, OSFs are produced in combination with various factors in the LSI manufacturing process. Therefore, it is not always improved even if a teaching is adopted to the manufacturing process as it is reported.
JP-A-3-217019 discloses that it is effective to preheating a wafer before oxidation in order to prevent generation of OSFs, since the crystal defects are liable to be produced on the wafer when the wafer is oxidized with damages caused by ion-implantation or plasma treatment. However, according to experiments by the inventors of the present invention, the generation of OSFs was not prevented only by hearing. It is required to find out a specific controlling technique for preventing the generation of OSFs.